Search Results (762)

In the present work, a bienzymatic voltammetric biosensor is reported for the simultaneous quantification of glucose and cholesterol in flavored milk samples with a single device. The biosensor is based on a carbon screen printing electrode on which paper disks impregnated with glucose oxidase and cholesterol oxidase, as well as ferricyanide as a mediator, are deposited. Linear voltammetry combined with an artificial neural network methodology were successfully used for the determinations, showing excellent agreement with the spectrophotometric reference method. Full article

Background: Kidney transplantation is the optimal treatment for end-stage renal disease; however, acute rejection remains a major determinant of long-term graft dysfunction and failure. Donor-derived cell-free DNA (dd-cfDNA) has emerged as a minimally invasive biomarker reflecting allograft injury, with growing evidence supporting diagnostic and prognostic utility. Objectives: This structured narrative review aimed to synthesize contemporary evidence (2020–2025) on the diagnostic and prognostic utility of plasma dd-cfDNA and its integration into kidney transplant rejection surveillance. Methods: A narrative literature review was conducted using PubMed to identify studies published or available online ahead of print, between January 2020 and September 2025, evaluating plasma dd-cfDNA in adult kidney transplant recipients. Manual screening of reference lists supplemented the search. Original clinical studies reporting diagnostic or prognostic outcomes were included, and the results were synthesized narratively due to methodological heterogeneity. Results: Across prospective and retrospective cohorts, elevated dd-cfDNA discriminated rejection from non-rejection biopsies, with strongest performance in antibody-mediated and microvascular rejection phenotypes. Longitudinal studies demonstrated that dd-cfDNA elevations often preceded histologically confirmed rejection and predicted adverse graft outcomes, while low levels were associated with immunologic quiescence. Assay variability limited cross-study comparability, whereas integration with donor-specific antibodies, gene expression profiling, or algorithm-based approaches improved diagnostic and prognostic discrimination. Conclusions: Dd-cfDNA is a clinically meaningful biomarker for kidney transplant rejection monitoring, providing diagnostic and prognostic information beyond conventional functional markers. When interpreted longitudinally and in clinical context, dd-cfDNA supports risk stratification and surveillance, with evidence supporting its expanding role in risk-adapted transplant care. Full article

Objective: The performance of chrono-impedance measurement, a novel electrochemical method for determining free fatty acids (FA), was evaluated in a real-world clinical setting. Methods: Patients presenting to the emergency department with chest pain or discomfort were included. Routine diagnostic tests were performed in accredited laboratories. Chrono-impedance was measured using a screen-printed carbon electrode connected to a dedicated potentiostat. Serum total free-FA levels were determined by gas chromatography with flame ionization detection. Results: Among 104 patients, 21 received a specific diagnosis, while the remaining 83 patients were discharged with non-specific pain. Mean free-FA level was 0.9 ± 0.6 mM. Palmitic, linoleic, stearic, oleic, and arachidonic acids accounted for 74.9% of total free FAs. Impedance plots showed a characteristic logarithmic increase over time for all patients. When instantaneous impedance values at four different time points (10, 100, 376.6, and 500 s) were examined, a significantly strong correlation was observed between impedance and FA molarity (r = 0.8312, 0.9897, 0.9947, and 0.9951) and FA weight (r = 0.9572, 0.9878, 0.9996, and 0.9998), respectively. Conclusions: Chrono-impedance demonstrated a very high correlation with total free-FA levels in real patient samples. Full article

We report a highly sensitive and interference-free electrochemical sensor for dopamine (DA) detection in the presence of uric acid (UA) and ascorbic acid (AA), based on an in situ deposited graphitic carbon nitride (g-C₃N₄) and polymethyl thymol blue (PMTB) nanohybrid modified screen-printed carbon electrode (SPCE). The as-fabricated g-C₃N₄/PMTB/SPCE was thoroughly characterized using various physicochemical techniques. The electrochemical behavior of the modified electrode was systematically investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The g-C₃N₄/PMTB/SPCE exhibited excellent electrocatalytic activity toward the selective oxidation of DA under optimized experimental conditions, including pH and scan rate. Interference-free detection of DA in the presence of AA and UA was achieved using DPV and chronoamperometric methods, revealing a wide linear concentration range, an ultralow limit of detection, and high sensitivity. Furthermore, the practical applicability of the proposed sensor was validated by determining DA in artificial biofluid samples, including blood serum, and urine. The recovery results obtained good agreement with those obtained using high-performance liquid chromatography (HPLC), confirming the reliability and accuracy of the developed sensing platform. Full article

Enzyme-free flexible glucose sensors hold great promise in the field of wearable health monitoring. However, their performance is limited by the balance between the catalytic interface activity and stability. This paper reports a strategy for interface gradient roughening of screen-printed carbon electrodes (SPCE) via controllable electrochemical exfoliation (EE). It systematically reveals the inherent relationships among the degree of EE treatment, electrode morphology, surface chemistry, and electrochemical performance. On this basis, the deposition of gold nanoparticles (AuNPs) with high density and uniform distribution is achieved, and a high-performance flexible enzyme-free glucose sensor is constructed. The study finds that EE treatment can significantly increase the true surface area of the electrode and introduce abundant oxygen-containing functional groups, thus effectively reducing the charge transfer resistance. Nevertheless, excessive exfoliation leads to the degradation of the conductive network, indicating the existence of a critical “performance window”. The EE-SPCE optimized with 150 cycles has both a high active area and good electrical conductivity, providing an ideal deposition substrate for AuNPs, increasing their distribution density by approximately 158% and reducing the average particle size to 125 nm. The fabricated AuNPs/EE-SPCE sensor exhibits excellent performance in glucose detection: it has a high sensitivity of 550.766 μA·mM⁻¹·cm⁻² in the range of 0.1–3 mM, a detection limit of 0.0998 mM, a wide linear range, excellent selectivity, long-term stability, and good mechanical flexibility. This research not only develops an efficient and scalable method for constructing flexible sensing interfaces but also clarifies the trade-off relationship among “roughening–conductivity–catalytic performance” at the mechanistic level, providing an important theoretical basis and a general strategy for rationally designing high-performance flexible electrochemical devices. Full article

Two approaches are described for construction of a screen-printed planar electrode (SPE) for potentiometric determination of iodide ion. The first, involves preparation and application of iron(II) bathophenanthroline tetraiodoplumbate complex ([Fe(bphen)₃][PbI₄]), as a sensitive and selective electroactive sensing material in a potentiometric electrode for iodide determination. The second is the use of a nano-sized poly(aniline-co-thiophene) (PANI-co-PT) as a solid-contact material in a planar miniaturized configuration. The SPE displays a Nernstian response for iodide ion with a calibration slope of −58.81 ± 0.69 mV/decade (R² = 0.9998) over a wide concentration range (9.17 × 10⁻⁷–6.94 × 10⁻³ mol/L), low detection limit (6.09 × 10⁻⁷ mol/L), rapid response time (5.0 ± 1.0 s) and long-life span (75 ± 3.0 d). The use of PANI-co-PT solid-contact layer significantly improves the ion-to-electron transduction, eliminates the formation of undesired thin water layer between the sensing membrane and the conducting substrate, prevents membrane delamination, enhances potential stability with a significantly reduced potential drift (8.32 ± 0.12 µV/min) and displays high redox capacitance (2.560 ± 0.040 mF). Water contact angle measurements confirm the increased hydrophobicity of the modified membrane electrode (from 44 ± 0.8° to 93 ± 1.4°) and demonstrate the membrane ability to repel moisture and further stabilize the sensor response. The proposed sensor is successfully integrated into a flow injection analysis (FIA) system to enable real-time and continuous iodide monitoring with high precision, high sample throughput and applicability for quality control of pharmaceuticals and environmental monitoring. Full article

Electrochemical biosensors are becoming increasingly prevalent across medical, food, and bioprocessing industries for monitoring complex biological processes. However, their sensitivity to contamination and exposure to potentially hazardous biological species often necessitates single-use disposal, contributing to the release of high-value, high-demand, and environmentally damaging materials into the environment. This study investigates the feasibility of a closed-loop recycling process for single-use glucose biosensors, with a focus on the recovery and reuse of noble metals silver and gold. Guided by ecodesign principles and using low-impact materials, we developed a silver screen ink, gold syringe ink, and a poly(lactic acid) (PLA) substrate. Sensors were fabricated by additive manufacturing and screen printing—enabling the scalability afforded by screen printing to produce the high-coverage silver layer while also minimising gold ink waste using additive manufacturing. A low-energy recovery method that exploited selective solvent compatibility was developed to reclaim silver and gold. Second-generation devices were then fabricated, demonstrating performance comparable to commercial equivalents while achieving an 80% reduction in material usage, cost, and environmental impact across 16 categories using a life cycle assessment (LCA). Full article

Indoor environmental quality significantly affects human perceptions of comfort and well-being due to the fact that most daily activities are spent indoors. However, surface colors are generally considered to be aesthetic choices rather than environmental factors. The purpose of this research is to assess the effect of surface colors on visual comfort, thermal intent, and plant-supportive lighting conditions. This study uses a controlled experimental method and four easily interpretable parameters: surface reflectance (albedo), illuminance, correlated color temperature, and photosynthetic photon flux density. The experiment uses a miniature enclosed chamber to standardize the geometry and lighting conditions to test a set of carefully chosen printed and painted color surfaces. The lighting parameters were directly measured using consumer-level spectral and illuminance meters. The surface reflectance parameter is estimated to be red, green, and blue color codes. The novelty of this research is that it provides a preliminary screening method that can convert color choice into quantifiable implications on indoor environments, with clear assumptions and limitations. The results can be used to inform design decisions that link color choice to specific task-oriented lighting requirements, climate-oriented thermal intent (cooler vs. warmer), and plant-rich interior environments. Full article

Early diagnosis of Alzheimer’s disease represents a critical clinical challenge, and the high-sensitive biomarkers measurement holds great potential for enabling early identification and intervention. This study proposes an electrochemical immunosensing strategy based on inkjet printing for the quantitative detection of Tau-441. Conductive patterns were formed by inkjet printing, followed by surface functionalization with gold nanoparticles to immobilize highly specific anti-Tau-441. This process created a stable and high affinity immunorecognition interface that enhances electron transfer and signal amplification. Furthermore, we developed and integrated a low-power portable detection platform to achieve a rapid detection process encompassing sample loading, signal acquisition, and on-device readout. The method shows a linear response from 50 fg/mL to 10 ng/mL and a limit of detection of 16 fg/mL (S/N = 3), with high specificity and good reproducibility. By combining scalable inkjet fabrication with a self-contained handheld reader, this method shortens the path from sample to result and offers a practical route for on-site screening and early intervention in Alzheimer’s disease. Full article

The blood-brain barrier (BBB) is one of the most selective physiological interfaces in the human body. Transendothelial electrical resistance (TEER) has become a widely adopted quantitative metric for assessing its in vitro structural and functional integrity. Although TEER measurements are routinely incorporated into BBB-on-chips, the absence of harmonized electrode architectures, measurement settings, and reporting standards continues to undermine reproducibility and translational reliability among laboratories. This systematic review provides the first comprehensive classification and critical comparison of electrode configurations used for TEER assessment, specifically within BBB-on-chip systems. Eligible studies were analyzed and categorized according to electrode design, fabrication method, integration strategy, and operational constraints. We critically evaluated six principal electrode architectures, highlighting their performance trade-offs in terms of uniformity of current distribution, long-term stability, scalability, and compatibility with dynamic shear conditions. Furthermore, we propose a bioinspired TEER reporting framework that consolidates essential metadata, including electrode specification, temperature control, viscosity effects, and blank resistance correction. Our analysis proposes screen-printed and hybrid silver-indium tin oxide (ITO) electrodes as promising candidates for next-generation BBB platforms. Moreover, our review provides a structured roadmap for standardizing TEER electrode design and reporting practices to facilitate interlaboratory consistency and accelerate the adoption of BBB-on-chip systems as truly biomimetic platforms for predictive neuropharmacological workflows. Full article

In this study, we present a new approach for detecting carbon dioxide based on the voltammetric behavior of selected pH indicators in a deep eutectic solvent (DES). The sensing strategy exploits the electrochemical oxidation potentials of acid–base indicators, in contrast to their conventional use in spectrophotometric analyses. For this purpose, a screen-printed carbon electrode (SPCE) coated with a thin film of DES containing an acid–base indicator was employed. This approach takes advantage of the unique properties of DESs, which make them safe and appealing electrolytes for gas sensing applications. It also exploits the behavior of acid–base indicators, which can exist in protonated or deprotonated forms with distinct oxidation potentials; the electron-rich basic form oxidizes at a lower potential than its protonated counterpart. Phenol Red (PR), Bromocresol Purple (BCP), and Bromothymol Blue (BTB) were investigated, and their voltammetric behavior was studied in different pH buffers as well as in reline DES. The pH dependence of their oxidation potential was used as the analytical parameter, varying in response to the concentration of acidic species in the gas phase. The proposed strategy was evaluated by performing CO₂ measurements, achieving limits of detection (LOD) and quantification (LOQ) of 2083 and 6875 ppm, respectively. The same approach was then applied to monitor food freshness via CO₂ detection, with results comparing favorably to nondispersive infrared (NDIR) methods for carbon dioxide analysis. Full article

This work used activated carbon material obtained by chemical activation of abundantly available agricultural sunflower waste residues to remove metol (4-(methylamino) phenol sulfate, MTL) from aqueous solutions. The adsorbent structure was characterized using SEM-EDS and FT-IR spectroscopy. A modified screen-printed carbon electrode (SPCE) with gold nanoparticles synthesized using the Laser Ablation Synthesis in Solution (LASIS) method was used to detect MTL. The successful LASIS formation of gold nanoparticles was confirmed by the specific dark burgundy–red color. TEM measurements showed uniform pseudo-spherical particles with an average diameter of 7.9 ± 0.2 nm. The modified electrode showed improved electrochemical activity, which was confirmed by comparing it with an unmodified electrode using cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode was subsequently used to optimize the MTL detection conditions. UV–Vis spectroscopy was used to optimize the adsorption conditions, with the optimal values for pH and contact time found to be 8 and 120 min, respectively. The electrochemical detection of MTL was performed using differential pulse voltammetry, and the linear calibration range was established for concentrations ranging from 0.73–49.35 µM. The obtained limits of detection (LOD) and quantification (LOQ) were 0.06 µM and 0.2 µM, respectively. The efficiency of MTL removal was 100% after a contact time of 1 min and remained at 100% after 120 min. Full article

Biomedical antennas are essential components in modern healthcare systems, supporting wireless communication, physiological monitoring, diagnostic imaging, and therapeutic energy delivery. Their performance is strongly influenced by proximity to the human body, creating challenges such as impedance detuning, signal absorption, and size constraints that motivate new materials and fabrication approaches. This work reviews recent advances enabling next-generation wearable and implantable antennas, with emphasis on printed electronics, additive manufacturing, flexible hybrid integration, and metamaterial design. Methods discussed include 3D printing and inkjet, aerosol jet, and screen printing for fabricating conductive traces on textiles, elastomers, and biodegradable substrates, as well as multilayer Flexible Hybrid Electronics that co-integrate sensing, power management, and RF components into thin, body-conforming assemblies. Key results highlight how metamaterial and metasurface concepts provide artificial control over dispersion, radiation, and near-field interactions, enabling antenna miniaturization, enhanced gain and focusing, and improved isolation from lossy biological tissue. These approaches reduce SAR, stabilize impedance under deformation, and support more efficient communication and energy transfer. The review concludes that the convergence of novel materials, engineered electromagnetic structures, and AI-assisted optimization is enabling biomedical antennas that are compact, stretchable, personalized, and highly adaptive, supporting future developments in unobtrusive monitoring, wireless implants, point-of-care diagnostics, and continuous clinical interfacing. Full article

Biofouling arises from non-specific adsorption of several components present in complex biofluids, such as full blood, on the surface of electrochemical biosensors, with a resulting loss of functionality. Most biomarkers of clinical relevance are present in biological fluids at extremely low concentrations, making antibiofouling strategies necessary in electrochemical biosensing. Here, we demonstrate the effect of a highly porous gold (h-PG) film electrodeposited on a gold screen-printed electrode (AuSPE) using a self-templated method via hydrogen bubbling as an antibiofouling strategy in electrochemical biosensor development following exposure of the electrode to bovine serum albumin (BSA) at two different concentrations (2 and 32 mg/mL). The h-PG film has a high electrochemically active surface area, 88 times higher than the AuSPE electrode, with a pore size ranging from 2 to 50 μm. A rapid decrease in the Faradaic current was observed with the unmodified AuSPE, attesting to the strong biofouling effect of BSA at both concentrations tested. Notably, the h-PG-modified electrode showed an initial peak current decline, more evident at a higher BSA concentration, followed by rapid electrode regeneration when the electrode was left idle in the biofouling solution. Similar results were obtained for unmodified and modified electrodes in real serum and plasma samples. The regeneration process, explained in terms of balance between h-PG pore size and protein size, the nanoscale architecture of the h-PG electrodes, and repulsive electrostatic forces, indicates the huge potential of the h-PG film for use in biomedical electrochemical sensing. Full article

The bioinspired superhydrophobic surfaces have demonstrated many fascinating performances in fields such as self-cleaning, anti-corrosion, anti-icing, energy-harvesting devices, and antibacterial coatings. However, developing a low-cost, feasible, and scalable production approach to fabricate robust superhydrophobic surfaces has remained one of the main challenges in the past decades. In this paper, we propose an uncommon method for the fabrication of a durable superhydrophobic coating on the surface of the glass slide (GS). By utilizing the screen printing method and high-temperature curing, the epoxy resin grid (ERG) coating was uniformly and densely loaded on the surface of GS (ERG@GS). Subsequently, the hydrophobic silica (H-SiO₂) was deposited on the surface of ERG@GS by the impregnation method, thereby obtaining a superhydrophobic surface (H-SiO₂@ERG@GS). It is demonstrated that the micro-grooves in ERG can provide a large specific surface area for the deposition of low surface energy materials, while the micro-columns can offer excellent protection for the superhydrophobic coating when it is subjected to mechanical wear. It is important to note that micro-columns, micro-grooves, and nano H-SiO₂ jointly form the micro–nano structure, providing a uniform and robust rough structure for the superhydrophobic surface. Therefore, the combination of a micro–nano rough structure, low surface energy material, and air cushion effect endow the material with excellent durability and superhydrophobic property. The results show that H-SiO₂@ERG@GS possesses excellent self-cleaning property, mechanical durability, and chemical stability, indicating that this preparation method of the robust superhydrophobic coating has significant practical application value. Full article